Star-branched polymers, also known as radial polymers, are characterized by having three or more polymer arms emanating from a central core. These polymers can be prepared by various polymerization procedures such as anionic, cationic, and free radical mechanisms. The stars are usually formed by using either multifunctional initiators, multifunctional chain transfer agents, or multifunctional coupling agents. The star polymers have unique properties including: narrow molecular weight distributions; low viscosities at low molecular weights or in solution due to their compact structures; and high viscosities at high molecular weights due to extensive entanglements.
The present invention is directed to amphiphilic star polymers which are effective as stabilizers of emulsion polymerization reactions as well as stabilizers of the emulsion polymer.